Kotest vs TestNG: What are the differences?

Introduction

Kotest and TestNG are both popular testing frameworks used in software development. While they serve similar purposes, they have some key differences that set them apart. This article aims to outline the main differences between Kotest and TestNG.

1. Test Execution Model: Kotest follows a coroutine-based execution model, allowing for asynchronous and thread-safe testing. On the other hand, TestNG follows a traditional method-based execution model, which utilizes annotations for defining tests and test suites.

2. Compatibility: Kotest is primarily focused on Kotlin language, providing a seamless testing experience for Kotlin projects. TestNG, on the other hand, is language-agnostic and supports multiple programming languages such as Java, Kotlin, and Groovy.

3. Test Configuration: Kotest offers a more flexible and intuitive configuration approach, allowing developers to define test configurations through code. TestNG, on the other hand, relies on XML-based configuration files for test setup, making it more suitable for configuration-heavy projects.

4. Assertion Libraries: TestNG relies on various assertion libraries, such as TestNG assertions, Hamcrest, and AssertJ, to perform assertions in tests. Kotest, on the other hand, provides its own built-in assertion library with a clean and fluent API, which eliminates the need for external assertion libraries.

5. Parallel Execution: TestNG has built-in support for parallel test execution, allowing tests to be run concurrently across multiple threads or processes. Kotest, on the other hand, doesn't provide built-in parallel execution capabilities, although it is possible to achieve parallelism using Kotlin coroutines.

6. Test Report Generation: TestNG provides extensive test reporting capabilities, including HTML reports, XML reports, and custom report generation. Kotest, on the other hand, has limited built-in test report generation capabilities, although it can be integrated with third-party libraries or plugins for generating detailed reports.

In summary, Kotest and TestNG differ in their execution models, compatibility, test configuration approaches, assertion libraries, parallel execution support, and test report generation capabilities. These differences make each framework suitable for different types of projects and development environments.